My mother is Mary Anne COtnam of Pembroke, daugter of HB Cotnam Former Chief Coroner.She believes she know a Harvey Cotnam (Former Auditor General of Ontario in the 1960's) Who was a cousin of HB Cotnam. Not sure of the blood lines.HB Father Was IRA Delbert Cotnam of Cobden. Ira's Father was George Cotnam of Cobden.
My mother has heard of Vinton Cotnam but does not know the relation.I suspect that George Cotnam (1857-1940) may have had a brother. that you may be related to as HB COtnam believed he was a cousin of Harvey Cotnam( Assuming this is the Harv Cotnam you have listed).